June 2026, Volume 3, Issue 6

Author

Nisha Jose, Jayaprakash V, Indhumathy E, Thenmozhi Mani, Venkatachalapathy E and M Jayakumar

Abstract

Background: Accurate assessment of glomerular filtration rate (GFR) is central to nephrology practice, yet measured GFR (mGFR) using exogenous markers is impractical in routine settings. Estimated GFR (eGFR) equations such as the CKD-EPI and MDRD are widely used but have limited validation in Indian populations. This study aimed to compare the accuracy, bias, and precision of CKD-EPI, MDRD, and the indigenous Prabhat formula against mGFR measured by diethylene-triamine-penta-acetic acid (DTPA) scintigraphy. Methods: In this prospective single-centre study, 141 adults undergoing DTPA GFR estimation were evaluated. eGFR was calculated using CKD-EPI, MDRD, and Prabhat equations. Accuracy was defined as the percentage of values within ±30% of the reference (P30). Bland-Altman plots were used to determine bias, precision, and relative error. Results: The mean DTPA-GFR was 71.2 ± 23.5 mL/min. Mean eGFRs were 85.9 ± 29.4 mL/min for CKD-EPI, 83.9 ± 34.4 mL/min for MDRD, and 68.2 ± 26.4 mL/min for Prabhat. The Prabhat formula showed the highest accuracy (P30 = 74.6%), followed by MDRD (61.1%) and CKD-EPI (57.5%). Bias was lowest with Prabhat (2.5 mL/min), while CKD-EPI demonstrated the best precision (38.5). All three equations correlated strongly with DTPA-GFR (r = 0.65-0.73). Conclusions: Although none of the equations met the benchmark P30 ? 90%, the Prabhat formula demonstrated superior accuracy, whereas CKD-EPI provided the best precision and least relative error. Validation of region-specific equations such as the Prabhat formula may enhance GFR estimation reliability in Indian patients.